Chamfers on gears for easing the axial meshing engagement of synchronous tooth systems, sliding gears and similar transmission parts are manufactured today mostly by a milling operation utilizing an indexing method and a pushlike feed ("push milling") on tooth-edge milling machines especially designated for this type of work. (Werkstatt und Betrieb, 95th year (1962), Issue 3, Pages 139 to 143). For adjusting the tool to the correct position relative to the workpiece, five auxiliary or adjustable axes are needed. Therefore, for a two-spindle push milling machine, aside from the three operating axes (one for the workpiece and two for the two tools) no less than 10 auxiliary axes are needed. Little attention was paid to this situation in the past, where the auxiliary axes were adjusted manually with simple means. However, this situation becomes of considerable importance for the future, particularly when the auxiliary axes for achieving a high degree of flexibility in the manufacturing devices are used and simultaneously therewith a short change-over time is needed and must be adjusted automatically. These considerations must be preprogrammed. It can easily be recognized that such machines can be changed over only with a considerable amount of structural and technical input to facilitate use in a flexible manufacturing situation.
Chamfers produced by shaping with a shaper tool are manufactured comparatively rarely (German AS No. 1 047 578), however, this method up to now has not been successful. Since for changing over less auxiliary axes are necessary, the possibility for a use in a flexible manufacturing situation results. However, it is disadvantageous that the V-shape of the chamfer which is to be produced can vary only within very narrow limits.
therefore, the basic purpose of the invention is to provide a method for the "shaping" of chamfers and an apparatus which is suited therefor, and which facilitates the manufacture of various chamfer shapes, namely both on externally and also on internally toothed parts.
The method is not only suited to produce flat chamfered surfaces. It is also possible through modifications to a cam plate which controls the stroke movement to produce spherically convexed or concaved chamfer surfaces. The most often encountered form of the chamfer is the so-called "straight chamfer surface", however. The straight chamfer surface is characterized by a pair of angled, flat surfaces angled at about 90.degree. and by flat to slightly spherical chamfer surfaces. That this chamfer shape is capable of improvement results from the geometric relationships. A V-shaped chamfer can be viewed as an optimum, the chamber halves of which correspond to the cutaway portion from a multiple-thread screw having a spiral angle corresponding with the angle of the V-shape. Because of the coaxial arrangement of the parts which are to be moved into engagement with one another during a simultaneous rotation relative to one another, the spiral construction of the meshing engagement aid offers a satisfactory sliding of the two parts relative to one another and into engagement with one another without shifting the contact point or the contact line.
Such a meshing engagement aid in the form of a cutaway portion from a screw can be manufactured with the inventive method. It is preferable that the machining grooves extend in the direction of the indexing movement and not, as this is the case in milling, transversely thereto. The meshing engagement aid is provided preferably with a roundness at a ridge between chamfer halves, which is possible with the inventive method without any additional operational sequences. The roundness prevents a splintering or flaking off of the ridge during a striking by or on the countertooth.
To adjust this rocking lever so that the cutting edge of the tool hits centrally or at a desired distance eccentrically onto the workpiece tooth, the apparatus can be further developed by supporting the rocking lever on an adjustable eccentric. For effecting a cooperation of a cam plate and the rocking lever, a spring can be used to urge the rocking lever into engagement with the cam plate or the rocking lever can be guided between a pair of cam plates. The size of the movement of the rocking lever and thus the length of the tool stroke can be varied very simply by providing a conical surface on the cam plate and supporting the cam plate for axial movement. When the apparatus is to be used for deburring or chamfering, a further development, namely, adjustably supporting the axis of the rocking lever for movement in a plane defined by the workpiece axis and a radial of the workpiece, can be preferable in order to be able to also work the base of the tooth on a workpiece.
The cooperation of the workpiece spindle with the control shaft or the workpiece with the tool can occur both mechanically and also electrically. In the latter case, it is possible to produce a modification to the chamfer surface characteristic.